Work in progress focuses on the regulation of RNA polymerases durng various growth and develomental transitions. Emphasis is placed on transtions where highly quiescent tissue is induced to proliferate. Specific objectives include the following: a.) To develop an in vitro transcription system with RNA polymerase I and cloned ribosomal DNA that supports faithful transcription. To identify specific factors in tissue extracts that are required for faithful transcription and regulate the rate of this transcription. b.) To develop an in vitro transcription system with RNA polymerase II and cloned fragments of the cauliflower mosaic virus genome that supports faithful transcription. To identify specific factors in tissue extracts that are required for faithful transcription. To determine whether different subclasses of RNA polymerase II are equally capable of selective and accurate in vitro transcription. c.) To determine the functional significance of subclasses of RNA polymerase II. d.) To determine common subunits and immunological relatedness of subunits in the three classes of RNA polymerase within an organism and the same class of RNA polymerase in different organisms.